function proxy_on() {
    export http_proxy=http://192.168.100.247:7890
    export https_proxy=$http_proxy
    export no_proxy="192.168.0.0/16,localhost,127.0.0.1,192.168.100.0/24"
    echo "http_proxy  : ${http_proxy}"
    echo "https_proxy : ${https_proxy}"
    echo "no_proxy    : ${no_proxy}"
    echo -e "http/https proxy service has been opened"
}

function proxy_off(){
    unset http_proxy https_proxy
    echo -e "http/https proxy service has been closed"
}
